FujiFilm X-E2S vs FujiFilm X-E4: read noise comparison

The FujiFilm X-E2S was measured at 16 ISO settings from ISO 200 to ISO 6400. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (200) read noise is 1.55 DN, or 3.2 electrons at the sensor. From ISO 1600 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 2500 don't change analog gain (digital push). Full well at base ISO is about 31,649 electrons; unity gain is around ISO 410.

The FujiFilm X-E4 was measured at 24 ISO settings from ISO 100 to ISO 51200. Values are Bill Claff's (Photons to Photos) direct measurements from raw files.

At base ISO (160) read noise is 2.07 DN, or 1.9 electrons at the sensor. A second gain (dual gain) kicks in at ISO 500, cutting input-referred read noise by about 1.1 stop. From ISO 640 up the camera is effectively ISO-invariant: raising ISO further doesn't meaningfully lower shadow noise. Settings above ISO 2500 don't change analog gain (digital push). Full well at base ISO is about 14,194 electrons; unity gain is around ISO 150.